Pyke's Build
So I tried Pyke earlier today in pbe and I was rather surprised by the recommended item build. Judging from his play style, it's rather feast or famine. He goes in and hopes to kill the enemy because if he doesn't, he'll just die. Because of this, I think the best build would be a bruiser build, like that of Vi or Irelia. Just because his passive makes him unable to get bonus health doesn't mean he can't build armor/mr. The tanky items he builds gives hp, which would then be transformed to ad instead.
A build I've been experimenting with is Iceborn Gauntlet, Randuins Omen, Frozen Heart, Thornmail with boots and support wards. You can go Spirit Visage if there are mages. Because most of these items also give hp, they give ad too. This would then help the sheen effect from Iceborn. The armor makes him semi-tanky while doing a decent amount of dmg. This build is considerably cheaper than the items on the recommended items like Duskblade, Black Cleaver etc. I think this may be the best build for him, but I'm not sure.